Over 50 percent of the world s population are infected with Helicobacter pylori (HP), an organism known to contribute to the pathogeneis of gastritis, duodenal ulcers and gastric lymphoma. Recent studies suggest that the HP urease is an important pathogenic protein and a promising target for passive immunotherapy using monoclonal antibodies. This laboratory has pioneered proprietary methods for the production of secretory IgA antibodies in transgenic plants (Ma et al. 1995). SlgA plantibodies are the preferred form of antibody therapy for topical, oral or enteric use. The overall goal of this project is to produce a therapeutic anti-HP urease plantibody. In Phase I we will construct secretory lgA forms of anti-HP urease antibodies, transform alfalfa by particle bombardment, select plants expressing assembled SlgA and evaluate the in vitro activity of purified anti-urease SlgA. In phase II feeding experiments will be carried out to demonstrate oral immunotherapy of Helicobacter infection in a rodent model. If results are positive preclinical development will be initiated. Anti-HP antibodies will provide a novel, safe and inexpensive therapy for this major human pathogen. PROPOSED COMMERCIAL APPLICATION An effective, inexpensive, easily administered immunotherapy for Helicobacter pylori infection has enormous potential with a significant market opportunity.